Rotary impact tools



Oct. 29, 1963 o. J, swENsoN ROTARY IMPACT TooLs 2 Sheets-Shea?.- 2

Filed oct. 21', 1960 N V R0 wwmw mw M mvmw Jin W. (j w Y B .All .c

United States Patent O grasses noranr uriner roots @scar l'. Swenson, Sunset Hill Drive, Branford, Conn. Filed Get. 211, 1966, Ser. No. 64,119 I aims. (Cl. S-52.3)

This invention relates to an improved impact-producing tool preferably of manually operated type such, for examples, as Aare shown in my U.S. Patents Nos. 2,661,- 647, December 8, 1953; 2,844,982, July 29, 1958, and 2,954,714, October 4, 1960l (SN. 773,229). Each of those patents, in common with the presen-t application, shows a manually operable impact wrench utilizing a main or power spring and an annular inertia or rotor member which carries pawl elements operating on an (eg.) ratchet-toothed portion of an output shaft or tool head to produce, through force stored in and released by the spring, successive sharp and powerful impacts, v-ia the tool head, as on a screw threaded fastener (bolt or nut) Y to tighten or loosen it. In the last mentioned patent (hereinafter sometimes referred toas patent No. 3) the power spring, `as in the tool of the present application, is a helical coil compression spring disposed lengthwise of and fully enclosed by a tubular portion of a handle member of the wrench; but said handle member in the patent required several parts adapted for heavy duty operation. In the present subject wrench the handle member is considerably simplified for easier manufacture and is otherwise especially adapted to serve `for light duty wrenching service.

bjects or novel lfeatures of the present invention include provision of an improved pawl and ratchet mechanism and associated part-s enabling the inerti-a member or rotor to be made inexpensively from sintered powdered metal or `from integrally joined sheet metal stampings; a simplified and inexpensive main or power compression coil spring assembly construction; an improved sheet metal handle construction capable of rapid 'and secure assembly with other parts so as, if desired, to completely enclose all but output shaft portions ofthe tool yand preferably so as to use the force of the power spring in latching or locking of fthe sheet metal components of the handle together.

Another object or novel feature is the pnovision of effectual shock absorbing means in the construction of stop members on the handle assembly and the rotor or inertia member, which stop members, when :in abutment, establish, through residual force in the power spring, an initial relative positioning of the handle and rotor after occurrence of each impact operation.

Another object is to provide a simple and effectual purpose-conversion means settable to condition the tool hereof selectively for operation as a rotary impact wrench and as an ordinary ratchet wrench.

Other objects and features of the invention will become apparent from the following description of the rotary impact tool mechanism as shown in the drawing wherein:

FIG. 1 is a top or lassembly plan view of an impact wrench hereof, partly in axial central section and otherwise generally as the tool would appear with one of two hollow sheet metal handle-constituting members removed.

FIG. 2 is `a fragmentary side elevation of the tool, partly in section as along the line 2 2 on FIG. 1.

FIG. 2a isa cross sectional view as indicated at Ztl-2a on FIG. 1.

FIG. 2b is a detail view of a spring and rotor connecting piece taken as indicated at 21a-2b on FIG. 1.

FIG. 3 is a `fragmentary view somewhat similar to FIG. 1 showing power-spring-associated modifications land a modified shock absorbing rotor stop construction.

FIG. 3a is a fragmentary side elevation of the tool head or output end portion of the -tool according to FIG. 3.

ice

FIG. 4 is a sectional view taken along the line y4 4 on FIG. 3 complementing the latter in showing one `form of latch or lock for holding portions of the handle-forming stampings together.

FIG. 5 is a reduced scale view of an inertia member or rotor positioned as in FIG. 2 and partly in central section, the vie-w showing more or less diagrammatioally the manner in which the rotor can be made wholly from identical sheet metal stampings.

General Arrangement In common with the torque 4transmit-ting impact tools of said patents, the tool lor tool assembly SW hereof comprises, as shown by comparison of FIGS. 1 and 2, an outpu-t shaft or tool head T hav-ing a ratchet toothed portion 10 coaxially thereof between its work engaging end portions 9 `and 11; a handle H extending laterally of the shaft; an annular inertia member or rotor W surrounding the ratchet toothed portion 1G; bearing means (eg. bushings 6, 7 rigid with the handle) guiding the shaft, handle and the Iinertia member for angular movement relative to each other about the 4axis L, FIG. 2, of 'the shaft; one or more pawls 4 mova-bly supported on the inertia member W as in associated recesses 4a therethrough and biased as by springs 4b for engagement with the ratchet teeth, and a cam or cams 3, one for each pawl, connected for movement with handle H as by being formed on the Ibushings 6 'and '7, and operable against the pawls as `a function of predetermined angular movement of the handle and inertia member W in a predetermined direction to enable successive escapements and impacts Ibetween the pawls and the ratchet teeth. f

Essentially as in patent No. 3, a coiled compression power spring S within the handle lengthwise thereof operatingly connects the handle to the inertia member W eccentrically thereof or in such manner that said predetermined relative angular move-inent of the handle and inertia member will, pursuant to said escapements, produce said impacts through energy alternately stored in and released by the spring S. As will be evident from FIG. 1, clockwise movement of the handle H will axially compress spring S if the tool head T does not move angularly and, assuming three pawls hence three cams 8 and twelve ratchet teeth, escapement and impact occurs for each such 'angular movement of the handle somewhat more than The cams are preferably so designed that approxnnately 37 movement of the handle is required between success1ve impacts.

As shown |by comparison of FIGS. 1 -and 2 the hollow handle I-I supports the bearing bushings e and 7 which may for example be welded to parallel side plate portions 2 land 3' of shells 2 and 3 respectively which preferably form the handle Xas will be further described. Cylindrical journal portions 5 and 5" of the output shaft or tool head T are snug in aligned bores 6' and 7' of the bushings; and diametrically enlarged ratchet-toothed portion 10 of the tool head is positioned by iand between mutually facing or proximal surfaces of the ybushings via the side plate portions 2 and 3i. Those side plate portions, radially outwardly of the bushings, overlap and retain in position iaxially the rotor W and its pawls 4. The illustrated square stubs 9and 11 of tool head T-usually engage sockets in suitable adapters (not shown) having additional sockets lor stubs complementary to the work. Stubs 9 and 11 are operatingly engaged with the work selectively according to whether the fastener is to be loosened or tightcned.

The sheet metal half shells Zand 3I (similarly shells 2a and 3a in FIGS. 3 and 3a) are securely and demountably held together in the region of tool head T, preferably in the same manner as in my said patents, namely by spring 3 metal snap rings R in respective grooves formed in the cylindrical portions 5 and 5" of the tool head. The snap rings are yapproximately in abutment with the side plate portions 2 and 3' respectively.

Handle Construction Handle H of the present impact wrench SW is constituted or formed mainly by two relatively heavy mutually complementary metallic half shell stampings 2 and 3 of operatingly identical shape and which, as viewed similarly to the showing of shell 3 in FIG. l, are bisymmetrical about the longitudinal axis L of the handle. Between the two ends of the handle the stampings are gradually narrowed from opposite directions, establish` ing a more or less cylindrical neck at region H; and near the free end portion of the handle remotely of the tool head T the cross section is gradually enlarged and then diminished to form a generally bulbous hand-hold portion H merging gradually with region H. Portion H is generally oval or at least non-circular in cross section as shown for example in FIG. 2a (cf. FIG. 4). Leftwardly diverging side wall portions of each shell (as at 3a and 3b FIG. l) come substantially into abutment with peripheral surfaces of the rotor W so that only cylindrical peripheral surfaces of the rotor are ever exposed; and the handle-constituting shells 2 and 3 are completed in the region of the rotor by the parallel flat side portons 2' and 3 which partially cover the ends of the rotor and support the bearing bushings 6 and 7 as clearly shown in FIG. 2.

At the outer or free end of the bulbous hand-hold portion H" the shells 2 and 3 have complemental end wall formations 24 (described later) forming parts of a supporting or base assembly 2t) for a power-spring-forceestablishing screw 22, which assembly includes releasable means (to be described later) for latching or locking the hand-hold portions of the shells 2 and 3 together.

Power or main spring S, assuming the spring, as shown in FIG. 1, to be subjected to some axial compressive stress, is self-supporting in the hollow handle H between, on the one hand, a push rod or link supported at one end solely by a laterally llexible end portion of the spring (FIGS. 1 and 2b) and which has a rounded head 15a detachably engaging a mating trough shaped seat 16 on the rotor W tangentially or eccentrically of the rotor axis and, on the other hand, the assembly via its screw 22. The screw 22 has a rounded or conical tip 22 seated in a complementary axial socket in a head 17 of a rod or bar 17 which extends a considerable distance within the coils of the rightward or outer end portion of the power spring S and holds those coils in approximate alignment. Push rod 15 (left, FIG. 1;-cf. FIG. 2b), has a shank portion 15' (shown curved), shouldered at 15" for operative abutment with the adjacent end coil of the spring S. The curved portion 15 of push rod 15 and the rod 17, each for approximately their entire lengths, are fairly loose in their associated spring coils or so as to enable or permit free axial exing of the power spring S in a plane normal to the working axis L, FIG. 2, while initially tending to maintain the spring in its illustrated shape or form.

Additional support for the power spring S particularly in the reduced diameter or necked down region H of the handle and outwardly therefrom toward the screw 22, is provided by shell or guard trough device 18, whose main purpose is to prevent the spring from damaging the handle shells. Trough device 18 is made preferably, of heat treated metal or similar high wear resistant metal. Trough 18 is of C-shaped cross section (FIG. 2a) being maintained against turning out of its illustrated position about the longitudinal axis of the spring S by a ange assembly portion 18a, 13b which is held in place between the rightward end of the spring S and the head 17 of guide rod 17 by axial force of the spring. Portion 18b of the spring guide assembly, may, as shown in FIG. 2a,

be shaped for abutment angularly about the spring axis with the adjacent shell walls to prevent such rotational dislocation of the guard trough 18 as mentioned above. The head 15a of push rod 15 is preferably partly cylindrical as illustrated in FIG. l; and the mating trough or seat 16 in the rotor W for head 15a extends for the full height of the rotor parallel to axis L thereof. Further, the head 15a of the push rod is elongated (FIG. 2b) parallel to the axis L in a manner tending to stablize the leftward end of the power spring assembly against rotating out of proper position.

The just-above-described main spring and guide etc. arrangement avoids having to provide a cross head and pivoted link assembly such as would require several expensive precision-formed parts if made for example according to the above-'identified patent No. 3.

The spring-force-setting screw 22 (right FIGS. l and 2) is demountably and adjustably supported by threaded engagement with a non-rotary thrust plate 23 of generally cupshaped form, providing a continuous annular (circular or non-circular) flange 25 embracing the margins of inturned mutually complementary ilanges 24' on the respective end wall portions 24 of the handle-constituting shells 2 and 3. The head 22a of the screw, having for example a socket for an Allen type wrench, is shown in normal position in FIG. l jammed for example against the thrust plate 23 to hold the power spring in its desired full strength position. Such position can thus be easily changed by selecting diierent length screws 22.

The interengaging surfaces of flanges 24' and 25 are preferably rightwardly divergent toward the head of the screw 22 or otherwise so shaped as to force the shells 2 and 3 tightly together when the screw occupies its FIG. l position. FIG. 2 shows at 22x the position of the head of screw 22 when the power spring is fairly completely relaxed. By then pushing the head to its dotted-line-illustrated position 22a the hand-hold portions of the shells 2 and 3 are disconnected as will be evident.

In the construction shown in FIGS. 3 and 4 the power spring guide rod 17 of FIG. l is replaced by tubular rod 117 having a head 117 attached to it and extended toward the adjacent walls of the handle H in suitable fashion so that the head can turn only a negligible amount if any about the longitudinal axis of the power spring S. The screw 122 has its head 122e seated in a recess 56 in a thrust and shell-locking plate 123 corresponding to plate 23 of FIG. l. Thrust plate 123 has, as an alternative for the locking flange construction 24', 25 of FIGS. l and 2, a set of pins (four for example) parallel with the adjusting screw 122 for snug engagement with openings in the end wall portions 124 of the stampings 2a' and 3a. A spring arm 60 is attached to the head 117' and its free end extends through a hole in a slidable exible metal dirt guard plate 61 to show by its position the condition of compression of the power spring (power level).

Shock Absorbng Rotor Stops The initial or normal (FIG. l illustrated) relationship of the handle H to the rotor W and its contained pawl and ratchet mechanism is established by complementary stops including as shown a radially projecting lug 35 on the rotor and a pair of cooperating stop assemblies 36 which, optionally, can be non-yielding blocks rigid with associated portions of the handle or as shown in above patent No. 3. The abutment or stop faces 35a and 36a are brought together with potentially destructive force under various conditions of operation of the present wrench in tightening or loosening fasteners, as when incomplete strokes of the handle are effected during which the handle is released, as more fully explained in said patent No. 3.

In the impact wrenches SW and SW hereof two constructions are shown as examples of suitable means to minimize the forces involved in bringing to a stop and in proper position the rapidly moving rotor.

The cushioning stop assembly or unit 36 as shown in FIG. l comprises a metal cap 37 formed as a channel with diverging ilanges; a rigid metallic supporting block or anvil 33 of generally triangular form as shown in FlG. l and an interposed elastic cushion pad 39 such as a channel shaped piece of oil resistant rubber or elastomer the faces of which pad are complementary to inside and outside faces of the cap 37 and block or anvil 38 respectively and bonded thereto. The block or anvil members 38 of the two stop assemblies 36 may be secured to the respective side plate portions 2' and 3 of stampings 2 and 3 by rivets 38a in positions such that the side walls 2b and 3b of the handle members are in tight abutment with the anvil members effectively to integrate the latter with the handle. Self damping characteristics for unit 36 may be had by appropriate selection of material for pad 39.

A form of cushioned stop assembly constructionally similar to unit 36 but in which the non-metallic pad 39 is omitted (not illustrated) is in eifect a metal spring wherein the stop and anvil members 37 and 38 (stop comprising spring metal) are made nearly complementary to each other as by being designed so as to have a predetermined difterence of divergence between their juxtaposed surfaces. Such construction cushions shock by temporary elastic yielding of the flange portions of member 37 accompanied by damping frictional resistance to movement of the members into full mating contact. s

The all metal spring stop assembly 35', as shown in FIGS. 3 and 3a, may comprise a pair of relatively heavy vspring members or blocks 36 attached to respective handle members 2a and 3a. The section of each spring member 36 is of such dimensions that the force of the rotor stop 3S on striking the face of the spring stop as suggested in FIG. 3 causes the stop to yield, absorbing some of the impact, meanwhile rapidly decelerating the rotor. The force on the stops 36 is less than on a xed stop (not shown) because the spring stop will yield slightly when the `rotor stop '35 strikes it. Each spring member 36" as shown in FIG. 3 is generally U-shaped providing a iixed arm or anvil portion 38 suitably secured to the associated handle member as by a rivet 38a in tight abutment with side wall portions 2b and 3b and a flexible arm or cushion portion 37 separated by a gap 39' of proper small dimension from the fixed arm. The arms 37 and 38 when brought into abutment t us serve as would a limiting fixed stop to prevent the rotor W from passing a specifically determined point. The dimension of the gap 39' is chosen so as to limit the relative deflection of the spring arms to a distance within the elastic limit of the metal. The force with which the defining surfaces of the gap 39 strike each other is always less than the force of stop SSagainst a fixed abutment (as in patent No. 3) because of the reduction in striking energy resulting from deceleration of the rotor while deflecting the free arm 37 of the spring stop.

Operation In the ratchet and cam mechanism as shown at the left in FIGS. l and 2, assuming the stub ll. of FIG. 2 on the tool head T is operatingly engaged with a right hand threaded fastener, not shown, the ratchet pawls 4 will have their end portions in engagement and escapement relationship with the generally radially extending faces of the ratchet teeth, and operation of the handle H in a clockwise direction as indicated by the arrow in FIG. l will tend to tighten the fastener during successive impacts. The pawls 4 have sulicient space in their sockets or recesses da in the rotor W defined in part by respective end portions il so that the pawls can move to disengage the ratchet teeth; and, as more elaborately explained in all three of said patents, the pawls 4 are forced as by the cam surfaces 8 of `bushings 6 and 7 out oi engagement with the teeth after approximately a 37 angular motion of handle H. Movement of the handle H as mentioned increases the energy in or compression of the power spring S so long as the pawls remain obstructed against angular movement with the handle (tool head 5 remaining stationary); wherefore as soon as the pawls are moved out of abutment with their associated ratchet tooth faces by the cam surfaces 8 as a function of overrunning of the handle relative to the inertia member and tool head, the highly stressed power spring S suddenly turns the rotor W until its pawls 4 forcibly strike the next adjacent set of tooth faces. The rotor W is designed with sufficient inertia so that the just described escapement and torsional impact operation of the tool SW is highly effectual in freeing frozen threaded fasteners and of course in tightening such fasteners to predetermined bolt tension values.

Ratchet Wrench Conversion Feature It has been noted that in order for the tool SW to operate as described the stop faces a and 36a must be separated between successive impacts distances somewhat greater than the 30 angular spacing of the ratchet teeth. If such separating movement is blocked then oscillating or indexing movements of the handle (e.g., greater than 30 degrees) will result in pure 30 ratcheting actions of the tool on an associated fastener. Selective blocking at the will of the operator is accomplished as illustrated principally in FIG. l by a pawl or lever pivotally mounted 'on one of the side plate portions 2' or 3 and having an externally exposed operating handle 46. The position of the lever 45 for enabling ordinary ratchet wrench action is indicated at 45x.

Rotor Construction The herein disclosed construction of rotor W and associated parts enables the rotor to be economically manuvfactured from sintered powdered metal by conventional `.means in separable dies as well understood in the metal Working arts, and, alternatively, to be economically made from identical integrally joined sheet metal stampings.

Making the rotor W by either of the just above mentioned techniques is practicable because all the openings (central bore for the ratchet wheel portion l() of the tool head T and the recesses 4a for the pawls) and also all external surfaces (stop face, 35a and main spring connection seat i6 being the critical ones) are parallel to working axis L and extend from end to end of the rotor, and no difficult-to-form small radii or sharp corners are necessary. Y

Since the pawls 4 in the present case can get out of their sockets la only by movement tangentially of the central 1core of the rotor for receiving the ratchet wheel y lll it is possible to block all but the operating pivotal movements of the pawls by forming arcuate stop surfaces in the rotor block concentric with the pivot axes of the pawls for abutment with the pawl tips. The tips may but need not be formed complementary to the arcuate surfaces.

In the pawl and recess construction as shown by comparison of FIGS. l and 2 (one pawl 4 shown in FIG. 2) it may be noted iirst that the pawls are securely held by the handle side plates 2 and 3 against excessive movement in their sockets 4a parallel with tool axis L. Second the pawls are prevented from moving away from their pivot-constituting semi-cylindrical recess portions 4: by the arcuate recess surfaces 4l disposed close to the free ends of the pawls always overlying said free ends and which, as earlier mentioned, are concentric with the effective pawl pivot axes, y

The absence of sharp corners and small radii (avoided largely by omission of necked pivot-forming heads on the pawls such as are shown in said patents) is of course more important if the rotor is made of sheet metal stampings as in rotor W of FIG. 5 than when the rotor is made of powdered metal. The identical stampings w FIG. 5

require no holes for rivets or the like since the stampings can be more solidly held together by brazing than by the use of rivets or other fasteners which would require holes. Further the stampings w can be made of fairly heavy gage sheet metal (due to absence of small radii and sharp corners as well understood) thereby economizing in assembly time and reducing likelihood of warpage of the individual stampings incident to rapid change of temperatures involved in brazing, welding, etc.

I claim:

1. In a manually operable torque transmitting impact tool, said tool comprising an output shaft having a circular series of teeth thereon coaxially thereof, a handle having a handhold portion extending laterally of the shaft, an annular inertia member surrounding the teeth, bearing means guiding the shaft, handle and the inertia member for angular movement relative to each other about the axis of the shaft, a pawl movably supported on the inertia member and biased for engagement with the teeth, and a cam `connected for movement with the handle and operable against the pawl as a function f angular relative movement of the handle and the inertia member in a predetermined direction to enable successive escapements and impacts between the pawl and the teeth, the handle comprising two mutually complementary hollow sheet metal stampings having side plate portions overlapping the inertia member, means demountably connecting the side plate portions to the output shaft, cooperating means remotely of the shaft and demountably interconnecting the stampings to unify the handle, a coiled compression spring in the handle lengthwise thereof and operatingly connecting the handle to the inertia member in such manner that said predetermined angular movement of the handle and inertia member will, pursuant to said escapements, produce said impacts by energy alernately stored in and released by the spring, said means interconnecting the stampings remotely of the output shaft including a device disposed inside the handhold portion and operatingly connected with the spring so as to be maintained, by force exerted by the spring axially thereof, in interlocking engagement with portions of the two stampings which constitute end walls of the handle.

2. The tool according to claim 1 wherein said device is an annular member having a central opening permanently exposed between said end-wall-constituting portions of the stampings, and a spring-force-establishing screw in threaded engagement with a device in operative t abutment with the spring axially thereof, the screw having a head portion accessible through the annular member from a position externally of the handle to enable rotational adjustment of the screw.

3. The impact tool according to claim l whenein the handhold forming portions of the stampings have flange portions complementing each other to form an end wall for the handle, and a power-spring-force-establishing screw is supported by a thrust plate movable into locking engagement with said flange portions detachably to hold the stampings together.

4. The impact tool according to cla-im 3 wherein the flange portions are turned inwardly so as to extend generally parallel to the longitudinal axis of the handle, and the thrust plate has a single annular ilange movable into embracing relation to the inturned flange portions.

5. A torque transmitting impact tool, comprising an elongated handle member, a tool head member having a `series of equally spaced circumferentially disposed teeth, an inertia member, bearing means guiding said members for relative angular movement about a common axis, a ,pawl movably mounted on the inertia member, turning therewith about said axis and spring biased toward the teeth for movement into and out of abutting relationship ywith the teeth, and power spring and cam mechanism 'between the handle member and inertia member and capable of operation as a function of angular overrunning movement of the handle member relative to the inertia member and tool head member to cause escapement and impact-producing reengagement of the pawl with said teeth, said mechanism including a helical spring and means securing one end portion thereof in fixed position on the handle remotely of the inertia member while enabling compression and elongation of the spring, the 0pposite end portion being flexibly movable laterally in a plane normal to said axis, and a push rod supported at one end solely by the iiexibly movable portion of the spring, the other end of the push rod being connected to transmit torque to the inertia member.

6. The tool according to claim 5 wherein said other end of the push rod is a generally rounded head detachably mating a complementary socket on the inertia member.

7. In a manually operable impact tool `comprising a rotary tool head, a hollow handle extending transversely of. tool head axis, an annular inertia member around the tool head, and bearing means guiding the tool head, handle and inertia member for relative angular movement about said axis; a ratchet wheel operatingly integral with the tool head, a pawl movably supported on the inertia member, biased for engagement with the ratchet wheel and disengageable from the ratchet wheel, and cam means rigid with the handle around said axis and operatingly connected with the pawl to disconnect it from, for reengagement with, the ratchet Wheel to impart torque-producing impact to the tool heads; an elongated compression spring within the handle for storing and releasing energy for such impacts, means supporting one elongated end portion of the compression spring in fixed relation to the handle while allowing the spring to contract and expand longitudinally during operation of the tool, an opposite end portion of the spring being free from said spring supporting means so as to flex laterally, an axially rigid push rod supported at one end solely by the free end portion of the spring, the opposite end of the push rod having an abutment connection with the inertia member remotely of said axis and so disposed as to compress the spring as a function of relative angular movement of the handle and inertia member.

8. In a torque transmitting impact tool, a torque input member, a torque output member having a series of equally spaced ratchet teeth, an inertia member, bearing means guiding said members for angular relative movement about a common axis, a pawl pivotally carried by the inertia member and spring biased toward the teeth for movement into and out of abutment relationship therewith, power spring and cam mechanism interconnecting the input member and inertia member in a manner to cause escapement and impact-producing reengagement of the pawl with said teeth as a function of predetermined angular relative movement of the input member and inertia member in a predetermined direction, cooperating circumferentially engaging stop surfaces on the input member and inertia member respectively and which are separated during said relative angular movement of the input and inertia members, and a device settable on the handle into and out of a position blocking predetermined separating relative movement of the stop surfaces for selective ratchet and impact wrench operation of the tool.

9. In a torque transmitting impact tool, `a torque input member, a torque output member having a series of equally spaced teeth, an inertia member, bearing means guiding said members for angular relative movement about a common axis, a pawl carried by the inertia member and spring biased toward the teeth for movement into and out of abutment relationship therewith, and power spring and cam mechanism interconnecting the input member and inertia member for causing escapement and impact-producing reengagement of the pawl with said teeth, stop members carried by the inertia member and input members respectively and movable relative to each other angularly about said axis during said escapement and at times 60ming into forcible abutment with each other, one of said stop members incorporating shock absorbing means.

10. The impact tool according to claim 9 wherein the shock absorbing means include elastic non-metallic cushion material.

11. The impact tool according to claim 9 where-in said one of the stop members comprises a metal channel having flange portions dverging away from the other stop member and a cooperating rigid support having similarly diverging surface portions.

12. The impact tool according to claim 11 wherein the diverging surfaced members are secured together by a layer of rubber or elastomer bonded to the diverging surfaces.

13. The impact tool according to claim 9 wherein said one of the stop members includes -a metal spring and the other step member is brought into frictional damping engagement with the spring during flexing of the spring.

14. The impact tool according to claim 9 wherein said one of said stop members is a metal spring having abutment means limiting the flexing movement thereof under impact.

15. The impact tool according to claim 14 wherein said one of the stop members is a U-shaped piece of spring metal having mutually adjacent but spaced apart arm portions so disposed in the tool that the force involved in such forcible abutment tends to flex one of the arm portions into arrested contact with the other arm portion.

References Cited in the rile of this patent UNITED STATES PATENTS Re. 19,341 McNaught et al. Oct. 16, 1934 2,086,261 Douglass July 6, 1937 2,112,693 Douglass Mar. 29, 1938 2,578,687 Fish Dec. 18, 1951 2,661,647 Swenson Dec. 8, 1953 2,688,268 -Lear Sept. 7, 1954 2,776,588 Livermont Jan. 8, 1957 2,844,982 Swenson July 29, 1958 2,910,901 Ryd Nov. 3, 1959 2,954,714 Swenson Oct. 4, 1960 FOREIGN PATENTS 1,239,894 France July 18, 1960 

1. IN A MANUALLY OPERABLE TORQUE TRANSMITTING IMPACT TOOL, SAID TOOL COMPRISING AN OUTPUT SHAFT HAVING A CIRCULAR SERIES OF TEETH THEREON COAXIALLY THEREOF, A HANDLE HAVING A HANDHOLD PORTION EXTENDING LATERALLY OF THE SHAFT, AN ANNULAR INERTIA MEMBER SURROUNDING THE TEETH, BEARING MEANS GUIDING THE SHAFT, HANDLE AND THE INERTIA MEMBER FOR ANGULAR MOVEMENT RELATIVE TO EACH OTHER ABOUT THE AXIS OF THE SHAFT, A PAWL MOVABLY SUPPORTED ON THE INERTIA MEMBER AND BIASED FOR ENGAGEMENT WITH THE TEETH, AND A CAM CONNECTED FOR MOVEMENT WITH THE HANDLE AND OPERABLE AGAINST THE PAWL AS A FUNCTION OF ANGULAR RELATIVE MOVEMENT OF THE HANDLE AND THE INERTIA MEMBER IN A PREDETERMINED DIRECTION TO ENABLE SUCCESSIVE ESCAPEMENTS AND IMPACTS BETWEEN THE PAWL AND THE TEETH, THE HANDLE COMPRISING TWO MUTUALLY COMPLEMENTARY HOLLOW SHEET METAL STAMPINGS HAVING SIDE PLATE PORTIONS OVERLAPPING THE INERTIA MEMBER, MEANS DEMOUNTABLY CONNECTING THE SIDE PLATE PORTIONS TO THE OUTPUT SHAFT, COOPERATING MEANS REMOTELY OF THE SHAFT AND DEMOUNTABLY INTERCONNECTING THE STAMPINGS TO UNIFY THE HANDLE, A COILED COMPRESSION SPRING IN THE HANDLE LENGTHWISE THEREOF AND OPERATINGLY CONNECTING THE HANDLE TO THE INERTIA MEMBER IN SUCH MANNER THAT SAID PREDETERMINED ANGULAR MOVEMENT OF THE HANDLE AND INERTIA MEMBER WILL, PURSUANT TO SAID ESCAPEMENTS, PRODUCE SAID IMPACTS BY ENERGY ALTERNATELY STORED IN AND RELEASED BY THE SPRING, SAID MEANS INTERCONNECTING THE STAMPINGS REMOTELY OF THE OUTPUT SHAFT INCLUDING A DEVICE DISPOSED INSIDE THE HANDHOLD PORTION AND OPERATINGLY CONNECTED WITH THE SPRING SO AS TO BE MAINTAINED, BY FORCE EXERTED BY THE SPRING AXIALLY THEREOF, IN INTERLOCKING ENGAGEMENT WITH PORTIONS OF THE TWO STAMPINGS WHICH CONSTITUTE END WALLS OF THE HANDLE. 